Wasp Spray That Does Not Harm Bushes

Keeping your bushes healthy means using the right pesticides.

Wasps can benefit your garden by pollinating flowers and preying on garden pests, but they become pests when you disturb their nests and they respond by stinging. Some wasp sprays aren't safe to use around bushes, but you don't have to choose between your shrubs and your safety -- several options kill the wasps without sacrificing the plants.

Harmful Chemicals

Many wasp sprays use a pyrethroid compound as an active ingredient. It's a synthetic chemical that can harm your bushes if it comes in contact with the leaves. This chemical works for up to three weeks -- which is good for killing an entire nest of wasps, but bad for your shrubs when it's left on the leaves. Pyrethroids appear under many names such as prallethrin, lambda-cyhalothrin, allethrin or pyresin. Check the wasp spray label for environmental cautions; it should state whether it's dangerous to use around certain plants such as evergreen shrubs or vegetables.

Safe Chemicals

To get rid of wasps without harming your bushes, use a spray containing pyrethrin. Extracted from the pyrethrum daisy (Tanacetum cinerariifolium), this chemical has a short effective time frame, usually no more than a couple of days. You might need to reapply the spray after 48 hours if you still see wasps in the nest, but the chemical won't hurt established shrubs. It can harm new growth or seedlings, so only use it when the bush isn't actively growing. The pyrethrum daisy grows in U.S. Department of Agriculture plant hardiness zones 6 through 10.

Natural Options

Organic wasp control products typically won't hurt your bushes. Look for sprays that contain natural oils such as mint or clove oil. Spray these when the sun isn't shining directly on the bush's leaves. Although the oil won't hurt the bush if absorbed, it can enhance the sun's rays and burn the leaves in direct sunlight and high heat.

Things to Consider

With any type of wasp spray, wear protective clothing to keep the chemicals off your skin and to keep the wasps from stinging you. This includes long sleeves and pants, gloves, a hoodie or hat, and safety goggles. Keep children and pets away when you're treating the wasps and cover any ponds that have fish or other aquatic wildlife. Wasps come and go from the nest, so you might not kill them all with the first application. Spraying the nest in the late evening gives you the best chance of killing the most wasps after they return home to rest. Check the nest after 48 hours and spray it again if you notice any activity.